The present invention relates to sensing or scanning apparatus in general, and more particularly to improvements in scanning or sensing apparatus of the type wherein one or more conductors transmit signals from a target or object to be detected to a remote receiver.
In presently known scanning or sensing apparatus of such character (hereinafter called sensing apparatus for short), the conductor which connects a remote target or object to be detected with a receiver is a copper wire. The target can be moved to and from a detectable position by a pushbutton or key which is mounted in a control panel or the like. A drawback of conventional sensing apparatus is that the fields of their application are limited. For example, such apparatus cannot be used in areas of pronounced electrical noise and/or in areas which are not explosion-proof. Thus, if the target is located in a region of pronounced electrical noise, the conductor is likely to transmit signals at a time when the target is or should not be detected. Furthermore, electrical conductors are likely to cause explosions as a result of spark generation at the locus where the target is to be moved into or from view by a pushbutton or the like.